Abstract:The explosion of the Deepwater Horizon drilling rig in the Gulf of Mexico on April 20, 2010, and
the resulting oil spill began a cascade of effects on the coastal areas of the Gulf and on the wealth
of species that inhabit those areas. These wetlands, like those elsewhere, have value for water
quality, flood control, shoreline protection, and recreation. They serve as nurseries for many
species, including fish and shellfish of commercial significance, waterfowl, and a host of resident
and migratory species. They also have cultural importance to the people of the Gulf. The effects
of the spill come on top of historic wetland losses due to subsidence, drainage, and saltwater
intrusion, along with rising sea levels, coastal erosion, and global climate change.

Impacts of oil spills on wetland ecosystems depend on multiple factors, including the type of oil,
exposure of the oil to weathering factors before it reaches the shore, the season in which the spill
occurs, etc. Estimating wildlife impacts is particularly difficult in this case because the spill
occurred far offshore, and the initial wildlife mortality came far out in the Gulf, where animals
sank without reaching the shore. With the arrival of oil closer to the shore, more animals could be
counted. Moreover, because the Gulf wetlands host many species of birds during seasonal
migrations, impacts of the spill could be felt in areas well away from the Gulf. Mitigation and
cleanup of damage to wetlands is far from an exact science and involves many tradeoffs: there is
no single, best solution. This report describes a range of options from mechanical recovery and
use of dispersants to doing nothing.

Among other issues is a seemingly simple question: who decides what to do? But the answer is
complex. The organizational structure for deciding how to respond to oil spills is specified in the
National Contingency Plan (NCP), which was created administratively and has been broadened
by the Clean Water Act, the Superfund law, and the Oil Pollution Act. Under the NCP structure,
the Coast Guard is the lead federal agency for overseeing response and cleanup. Oil has reached
more than 10% of Gulf shoreline, but until oil from the well stopped flowing, very little cleanup
of wetlands was occurring, because of both the ongoing risk of greater harm from cleanup and the
potential for re-oiling. As cleanup proceeds, a number of questions arise. To cite only two, what
factors will determine cleanup strategies, and how are needs to improve scientific understanding
of the spill’s impacts being considered?

Decisions about cleanup of wildlife are no easier. Cleanup of individual animals is laborintensive,
and some scientists argue that the survival of an animal that has been cleaned is so
uncertain as to call into question whether treatment is, in fact, humane. Rescue groups are
dedicated to salvaging those that can still be saved. The effects on a species as a whole vary
markedly from one species to another, depending on that species’ abundance and ecological
needs; appropriate responses at the species level are unclear.

Additionally, the advent of hurricane season poses new risks to areas that may not otherwise be
affected directly by the spill. History, particularly from the relatively well-studied Exxon Valdez
spill of 1989, offers insight into the future of Gulf resources as well. First, some cleanup efforts
might do more harm than good in the long run. Second, it is not possible to predict all of the
ramifications for the complex Gulf ecosystem in the decades to come, but history suggests that at
least some effects will continue for decades. Finally, litigation could play a major role in
disseminating—or not disseminating—scientific information about the spill and its effects.